/*

 * Licensed to the Apache Software Foundation (ASF) under one

 * or more contributor license agreements.  See the NOTICE file

 * distributed with this work for additional information

 * regarding copyright ownership.  The ASF licenses this file

 * to you under the Apache License, Version 2.0 (the

 * "License"); you may not use this file except in compliance

 * with the License.  You may obtain a copy of the License at

 *

 *     http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

package com.bff.gaia.unified.sdk.io.gcp.bigquery;



import com.google.api.services.bigquery.model.TableRow;

import com.bff.gaia.unified.sdk.transforms.DoFn;

import com.bff.gaia.unified.sdk.transforms.SerializableFunction;

import com.bff.gaia.unified.sdk.values.KV;

import com.bff.gaia.unified.sdk.values.PCollectionView;

import com.bff.gaia.unified.sdk.values.ShardedKey;



/**

 * Receives elements grouped by their (sharded) destination, and writes them out to a file. Since

 * all the elements in the {@link Iterable} are destined to the same table, they are all written to

 * the same file. Ensures that only one {@link TableRowWriter} is active per bundle.

 */

class WriteGroupedRecordsToFiles<DestinationT, ElementT>

    extends DoFn<

	KV<ShardedKey<DestinationT>, Iterable<ElementT>>,

        WriteBundlesToFiles.Result<DestinationT>> {



  private final PCollectionView<String> tempFilePrefix;

  private final long maxFileSize;

  private final SerializableFunction<ElementT, TableRow> toRowFunction;



  WriteGroupedRecordsToFiles(

      PCollectionView<String> tempFilePrefix,

      long maxFileSize,

      SerializableFunction<ElementT, TableRow> toRowFunction) {

    this.tempFilePrefix = tempFilePrefix;

    this.maxFileSize = maxFileSize;

    this.toRowFunction = toRowFunction;

  }



  @ProcessElement

  public void processElement(

      ProcessContext c,

      @Element KV<ShardedKey<DestinationT>, Iterable<ElementT>> element,

      OutputReceiver<WriteBundlesToFiles.Result<DestinationT>> o)

      throws Exception {

    String tempFilePrefix = c.sideInput(this.tempFilePrefix);

    TableRowWriter writer = new TableRowWriter(tempFilePrefix);

    try {

      for (ElementT tableRow : element.getValue()) {

        if (writer.getByteSize() > maxFileSize) {

          writer.close();

          writer = new TableRowWriter(tempFilePrefix);

          TableRowWriter.Result result = writer.getResult();

          o.output(

              new WriteBundlesToFiles.Result<>(

                  result.resourceId.toString(), result.byteSize, c.element().getKey().getKey()));

        }

        writer.write(toRowFunction.apply(tableRow));

      }

    } finally {

      writer.close();

    }



    TableRowWriter.Result result = writer.getResult();

    o.output(

        new WriteBundlesToFiles.Result<>(

            result.resourceId.toString(), result.byteSize, c.element().getKey().getKey()));

  }

}